Opec’s mettle will be tested next week when the cartel assembles in Vienna at a hastily convened meeting to discuss the economic crisis and whether the exporters’ club should take action to arrest the fall in the price of crude oil. Mounting alarm over the dwindling rent from oil sales prompted Opec yesterday to bring forward an emergency meeting scheduled for mid-November to next Friday.

Together the cartel members have lost about a billion dollars of revenue a day since crude price peaked in July. The benchmark US Light crude price fell $5 per barrel on the New York Nymex exchange yesterday to $69.15 (£40.05), less than half the value at oil’s peak, while London’s Brent crude futures contract fell to $65.70.

Evidence of rising oil stocks in America and weakening demand for energy in China’s mills and workshops has speeded up oil’s decline, but there is no agreement within the cartel over price strategy. Opec hawks, such as Iran and Venezuela, want to shore up the price by turning off the taps, but neither country can afford to cut output and forgo revenues. Both are failing even to produce at their agreed quotas because of weak investment in their oil industries, so the burden of any cut will fall on Kuwait and Saudi Arabia.

The Saudis would not like to see the price falling below $60 per barrel, a level at which most economists reckon the kingdom can support its profligate princes, the social security bills and invest in the oil industry. However, the Saudis will be listening to the grinding cogs of the slowing Asian industrial juggernaut with mounting concern. A deep recession might precipitate an oil price collapse.

It is Saudi Aramco that has been responsible for the weakening oil price, pushing more oil on the market since the energy summit in Jedda. According to Platts, the oil pricing publisher, even as the price tumbles Saudi Aramco has supplied every refiner’s request to lift Saudi crude next month.

The wider question is what impact falling crude will have on nonOpec oil output. Russia’s budget depends on a $70 per barrel price, according to Aleksei Kudrin, the Finance Minister. But Russian oil output is already falling because of weak investment, as is Mexican production.

The major Western oil companies can probably stomach prices dipping temporarily to $60 for a few months and still pay their dividends, but a prolonged slump at $50 per barrel would lead to the scrapping of investments followed by another cycle of shortages and soaring prices.

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